Ironing system with water delivery mechanism

ABSTRACT

The invention relates to an ironing system ( 20 ) comprising a steam iron ( 200 ) and a base unit ( 250 ) adapted to cooperate with each other such that the steam iron ( 200 ) can take a first position (P 1 ) in which the steam iron ( 200 ) is docked on the base unit ( 250 ), and a second position (P 2 ) in which the steam iron ( 200 ) is undocked from the base unit ( 250 ). The steam iron ( 200 ) is cordlessly detached from the base unit ( 250 ) in the second position (P 2 ). The steam iron ( 200 ) comprises a water reservoir ( 201 ) arranged to store water, and a soleplate ( 202 ) for generating steam from water in the water reservoir ( 201 ) when the steam iron ( 200 ) is in the second position (P 2 ). The base unit ( 250 ) comprises a water delivery mechanism ( 251 ) for supplying water to the water reservoir ( 201 ) when the steam iron ( 200 ) is in the first position (PI), and a power supply unit ( 252 ) for supplying energy to the soleplate ( 202 ) when the steam iron ( 200 ) is in the first position (P 1 ), for heating the soleplate ( 202 ). The ironing system ( 20 ) further comprises a temperature sensor ( 203 ) for sensing temperature of the soleplate ( 202 ), a controller ( 253 ) for determining, based on a variation of temperature of the soleplate, an amount of water to be supplied to the water reservoir ( 201 ) by the water delivery mechanism ( 251 ). This solution allows an improved water fill-in of the water reservoir.

FIELD

The present invention relates to an ironing system with water deliverymechanism, in particular to an ironing system comprising a steam ironand a base unit.

The invention has some applications in the field to garment care.

BACKGROUND

A cordless steam iron with energy and water charging offers convenienceto users by freeing them from a cord, as compared to more traditionalsolutions in which energy and steam/water are provided by a cord. Acordless steam iron thus does not restrict freedom of movement of theuser.

However, the ability of generating steam in known cordless systems isnot optimal, since it has to be compromised due to the limited thermalenergy stored in the steam iron, and to the limited amount of waterstored in the steam iron.

This may result in situations where the thermal energy stored in thesteam iron is not sufficient to generate steam, resulting in waterspitting on the garments being ironed. This may also result insituations where the thermal energy stored in the steam iron issufficient to generate steam, but the water stored in the steam iron isnot sufficient and/or has been fully used-up.

There is thus a need to find solutions for cordless steam irons toensure a more optimal compromise between stored thermal energy forgenerating steam and water amount stored in the steam iron.

Prior art U.S. Pat. No. 6,176,026B1 discloses a cordless steam ironprovided with an external reservoir assembly for automaticallyre-filling an internal reservoir when the iron rests on an iron stand.The reservoir assembly includes a removable bottle that can be readilyfilled with water and then placed upside down in a water container. Avalve automatically maintains the water level in the container (and theinternal reservoir) to a desired maximum level see chain-dotted line A.Water valves cooperate with one another and open automatically when theiron is placed on the stand, to allow water to flow from the containerto the reservoir.

SUMMARY

It is an object of the invention to provide an improved ironing systemthat substantially alleviates or overcomes one or more of the problemsmentioned above.

The invention is defined by the independent claims. The dependent claimsdefine advantageous embodiments.

According to an aspect of the present invention, there is provided anironing system comprising a steam iron and a base unit adapted tocooperate with each other such that the steam iron can take a firstposition in which the steam iron is docked on the base unit, and asecond position in which the steam iron is undocked from the base unit,the steam iron being cordlessly detached from the base unit in thesecond position.

The steam iron comprises:

-   -   a water reservoir arranged to store water,    -   a soleplate for generating steam from water in the water        reservoir when the steam iron is in the second position,

The base unit comprises:

-   -   a water delivery mechanism for supplying water to the water        reservoir when the steam iron is in the first position,    -   a power supply unit for supplying energy to the soleplate when        the steam iron is in the first position, for heating the        soleplate.

The ironing system is characterized in that it comprises:

-   -   a temperature sensor for sensing temperature of the soleplate,    -   a controller for determining, based on a variation of        temperature of the soleplate, an amount of water to be supplied        to the water reservoir by the water delivery mechanism.

A main contributor to the temperature drop of the soleplate is linked tothe amount of water consumed during steam ironing of garments.Therefore, the variation of the sensed soleplate temperature can be usedto determine the amount of water to be provided by the water deliverymechanism to the water reservoir when the steam iron is in the firstposition. Hence, an ironing system according to the above aspect candetermine the amount of water to be provided by the water deliverymechanism to the water reservoir when the steam iron is in the firstposition without using a water sensor in the steam iron. Moreover, thisreduces the manufacturing costs when compared to systems including awater sensor.

In some conventional systems, a pump is used at full power to fill awater reservoir of a cordless steam iron when it is docked until, forexample, the water reservoir is determined to be full by means of sensedback pressure. However, such conventional systems put stress on theseals and the piping system within the steam iron and/or base unit. Incontrast, using an ironing system according to the invention, thecontroller can achieve that a proper amount of water is supplied to thewater reservoir to reduce the side effects of water being over-suppliedand under-supplied, without using sensed back pressure. This can enablethat the water reservoir is filled-in to the proper or near correctamount, with reduced stress on the components of the steam iron and/orbase unit (e.g. seals).

In a preferred embodiment, the variation of temperature corresponds tothe difference between the temperature of the soleplate when the steamiron is in a current first position, and the temperature of thesoleplate when the steam iron was in a previous first position.

Measuring the drop of temperature between two successive docking in thefirst position, when the iron is just undock and when the iron is justdocked back, allows an estimation of the amount of water used duringironing, and thus fill-in the water reservoir with about the same amountof water when the steam iron is retuned in the first position.

In a preferred embodiment, the controller is further adapted todetermine the amount of water, based on a time duration between twosuccessive docking of the steam iron on the base unit.

On top of temperature sensing, adding the time duration between twosuccessive docking of the steam iron on the base unit allows a moreaccurate determination of the amount of water to be filled-in the waterreservoir. Indeed, the longer this time duration, the higher theprobability that non-steaming period of time have occurred as well, alsocontributing to causing a drop of temperature of the soleplate (althoughfor a combination of dry ironing and steam ironing the error margin isnot high because the heat energy used to convert water into steam ismuch higher than heat loss during dry ironing). Using the time durationbetween two successive docking of the steam iron, together with thesensed drop of temperature, allows a more accurate determination of thewater consumption.

In a preferred embodiment, the controller is further adapted todetermine, based on the sensed soleplate temperature, a thermal energyamount to be stored in the soleplate by the power supply unit, and todetermine, based on the thermal energy amount, the amount of water to besupplied to the water reservoir, such that the amount of water can befully transformed into steam by the thermal energy amount.

This allows a proper fill-in of water in the water reservoir, becausethe amount of water which is filled-in can be fully evaporated basedwith the thermal energy stored in the soleplate. This also allows thatthe steam iron can be undocked anytime from the base unit, whilesafeguarding that the amount of water filled-in the water reservoircould be fully evaporated. As a result, water spitting risk duringironing of garments that would be caused by a lack of thermal energy inthe soleplate will be reduced.

In a preferred embodiment, the temperature sensor is arranged in alocation taken from the set of locations defined by the base unit andthe steam iron.

Arranging the temperature sensor in the iron, and sensing soleplatetemperature directly, allows an accurate sensing of core temperature.When the steam iron embeds a source of energy to supply the temperaturesensor (e.g. battery), arranging the temperature sensor in the steamiron allows conducting temperature sensing even when the steam iron isundocked from the base unit.

Arranging the temperature sensor in the base unit allows an easyimplementation considering the relatively large space in the base unitand ease of wiring.

In a preferred embodiment, the controller is arranged in a locationtaken from the set of locations defined by the base unit and the steamiron.

Arranging the controller in the base unit allows an easy implementationconsidering the relatively large space in the base unit andaccessibility to continuous power supply. Arranging the controller inthe steam iron allows conducting calculations even when the steam ironis undocked from the base unit, provided that the steam iron embeds asource of energy to supply the controller (e.g. battery).

In a preferred embodiment, the steam iron comprises a heating elementfor receiving energy supplied by the power supply unit.

Using a heating element in the steam iron defines a cost-effectivesolution for heating the soleplate.

In a preferred embodiment, the heating element and the power supply unitare adapted to be electrically connected when the steam iron is in thefirst position.

Using this electrical connection between the heating element and thepower supply unit defines a cost-effective solution for supplyingelectrical energy to the heating element for thermal energy generation.

In a preferred embodiment, the base unit comprises an induction systempowered by the power supply unit for generating electromagnetic energytowards the steam iron when the steam iron is in the first position.

Using an induction system to provide energy to the steam iron avoids anyelectrical connector between the base unit and the steam iron.

In a preferred embodiment, the controller is further adapted to generatea first alert signal when the steam iron is in the second position, ifthe time duration elapsed since the steam iron was undocked from thefirst position exceeds a given time duration threshold.

The generation of this alert signal reminds the user to return the steamiron on the base unit if the undocked period is too long, which wouldanyway reflects the need to supplying energy to the soleplate and/orfill-in water in the water reservoir. As a result, the user can re-dockthe steam iron before the performance of steam generation is reduced dueto a lack of thermal energy and/or water. This can enhance ironingperformance.

In a preferred embodiment, the controller is further adapted to generatea second alert signal when the steam iron is in the first position,after the thermal energy amount is stored in the soleplate and theamount of water supplied to the water reservoir.

This alert mechanism allows informing the user that the steam iron isready for ironing. Hence, premature (i.e. too early) undocking from thebase unit may be avoided.

The present invention also relates to a method of determining, in anironing system as described above, an amount of water and energy to besupplied from the base unit to the steam iron.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic graph of temperature variation against waterconsumed during ironing;

FIGS. 2a and 2b show an ironing system according to the invention infirst and second positions, respectively;

FIG. 3 shows a schematic graph of temperature against time duringironing;

FIG. 4 is a flow chart of operation of an ironing system according tothe invention;

FIG. 5 shows a flow chart of a method according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 2a and 2b show an ironing system 20 according to the invention.The ironing system 20 comprises a steam iron 200 and a base unit 250.FIG. 2a represents the steam iron 200 in a first position P1 beingundocked from the base unit 250, while FIG. 2b represents the steam iron200 in a second position P2 being docked on the base unit 250.

The steam iron 200 and the base unit 250 are adapted to cooperate witheach other such that the steam iron 200 can take a first position P1 inwhich the steam iron 200 is docked on the base unit 250, and a secondposition P2 in which the steam iron 200 is undocked from the base unit250.

The steam iron 200 is cordlessly detached from the base unit 250 in thesecond position. In other words, no cords to carry electricity, water,signals, etc . . . are linking the steam iron 200 and the base unit 250.

The steam iron 200 includes a water reservoir 201 arranged to storewater. The steam iron 200 also comprises a soleplate 202 for generatingsteam from the water in the water reservoir 201 when the steam iron 200is in the second position P2.

The base unit 250 comprises a water delivery mechanism 251 for supplyingwater to the water reservoir 201 when the steam iron 200 is in the firstposition P1. The base unit 250 also comprises a power supply unit 252for supplying energy to the soleplate 202 when the steam iron 200 is inthe first position P1, for heating the soleplate 202.

The ironing system 20 further comprises a temperature sensor 203 forsensing temperature of the soleplate 202. The ironing system 20 alsocomprises a controller 253 for determining, based on a variation oftemperature of the soleplate, an amount of water to be supplied to thewater reservoir 201 by the water delivery mechanism 251.

The controller 253 may correspond to a microcontroller unit (MCU), ormore generally a processing unit or a calculator executing instructionsof a computer program stored in a local memory (not shown).

It will be appreciated that FIGS. 2a and 2b show the systemschematically, and that various electrical and water flowinterconnections (e.g. between the water reservoir 201 and the soleplate202) are not shown for convenience.

The determination of the water amount by the controller 253 will now beexplained in more details along with FIG. 1 and the following Table 1.

Temperature (deg C.) for a soleplate Water amount evaporated (g) havinga thermal mass of 500 g 0 200 0.5 197 1 194 1.5 190 2 187 2.5 184 3 1813.5 178 4 174 4.5 171 5 168 5.5 165 6 162

Table 1 is an example of the relation between the amount of waterevaporated by the soleplate, and the corresponding temperature of thesoleplate. This example is given for a soleplate having a thermal massof 500 g. The corresponding curve C1 is illustrated in FIG. 1.

For example, if the variation of temperature of the soleplate is betweenan initial temperature T0=190 degC and a final temperature T1=171 degC,it can be determined that the corresponding amount of water evaporatedthat caused this drop of temperature is m1−m0=4.5−1.5=3 grams. Thisamount of water evaporated corresponds to the amount of water determinedby controller 253 to be filled-in the water reservoir.

The above Table 1 can be stored in a memory in the steam iron or in thebase unit, as a thermal characteristic of the soleplate implemented inthe steam iron.

Alternatively, in case the temperature of the soleplate decreasesquasi-linearly with the amount of water evaporated by the soleplate, asillustrated in the example of FIG. 1, the curve C1 can be approximatedby a linear relation:

T=−6.33*m+200

The amount of water evaporated by the soleplate (and corresponding tothe amount to be filled-in) is expressed as follows:

(m2−m1)=(T1−T2)/6.33

So only the slope coefficient of the curve C1 (having absolute value6.33 in the present example) needs to be stored in memory. Thecontroller 253 then determines the amount of water to be supplied to thewater reservoir 201 by the water delivery mechanism by dividing thevariation of temperature by this slope coefficient. The slopecoefficient depends on the design parameters of the iron such as thermalmass, material used, etc . . . . For any given design, with requireddesign parameters, there is a corresponding curve that is stored andused by controller 253.

Preferably, the variation of temperature corresponds to the differencebetween the temperature of the soleplate 202 when the steam iron 200 isin a current first position P1, and the temperature of the soleplate 202when the steam iron 200 was in a previous first position P1.

The steam iron 200 comprises a heating element 204, a water interface205, and an electrical interface 206. In this embodiment, the soleplate202 comprises an ironing plate 202 a and a steam generator 202 b.

The base unit 250 includes a power supply 252, a water interface 255, anelectrical interface 256, an external water inlet 257, an external powerinlet 258, and a user interfacing means 259.

In this embodiment, the water delivery mechanism 251 comprises a watertank 251 a and a pump 251 b. The water tank 251 a of the water deliverymechanism 251 may also be provided separately to the apparatuscomprising the pump, for example by being arranged fluidly connected tothe base unit.

When the steam iron 200 is in the first position P1, the base unit 250provides water to fill the water reservoir 201. Water is pumped from thewater tank 251 a to the steam iron 200 by the pump 251 b via aconnection between the water interfaces 205 and 255 when the steam ironis in the first position P1. This connection can take many forms, andembodiments of the invention are not limited by any particular waterinterface type. The pump 251 b and the water tank 251 a provide thewater delivery mechanism 251 in this embodiment. However, otherembodiments can have other water delivery mechanisms.

When the steam iron 200 is in the first position P1, the base unit 250provides power to heat the soleplate 202. In this embodiment, the baseunit 250 provides electrical power to the heating element 204 whichheats the soleplate 202. The electrical power is provided from the baseunit 250 to the steam iron 200 via an electrical connection between theelectrical interfaces 206 and 256 when in the first position P1. Thisconnection can take many forms, and embodiments of the invention are notlimited by any particular electrical interface type.

During ironing, the steam iron is in the second position P2 and theironing plate 202 a contacts the garment. The steam generator 202 b, inthis embodiment, is a separate component to the ironing plate 202 a.Water from the water reservoir 201 is provided to the steam generator202 b, where it is heated using stored thermal energy of the steamgenerator 202 b. The steam can then pass through holes in the ironingplate 202 a in order to provide steam to the garment. In thisembodiment, the heating element 204 heats the ironing plate 202 a andthe steam generator 202 b when in the first position. While embodimentsare not limited to a particular arrangement of the ironing plate 202 aand steam generator 202 b, it will be appreciated that the ironingsystem may be arranged so that the heating element 204 heats the steamgenerator 202 b to a higher temperature than the ironing plate 202 a.This can maximise stored thermal energy.

In other embodiments, the soleplate 202 may be provided by a combinedironing plate and steam generator, e.g. a single plate for contactinggarments and generating steam.

The water tank 251 a is connected to the external water inlet 257 (e.g.mains water or a suitable inlet to enable the user to refill the watertank 251 a), and the power supply 252 is connected to the external powerinlet 258 (e.g. mains electrical supply).

Preferably, the controller 253 is further adapted to determine theamount of water, based on a time duration between two successive dockingof the steam iron 200 on the base unit 250. More explanation on thiswill be given with reference to FIG. 3.

FIG. 3 shows a graph of temperature along axis 1 (e.g. in ° C.) againsttime along axis 3 (e.g. in s). Dotted curve 5 a corresponds totemperature loss when dry ironing and plain curve 5 b corresponds totemperature loss when steam ironing.

When the user undocks the steam iron 200, the controller 253 measuresthe temperature of the soleplate to be T0, at time t0. Hence, T0 is thetemperature of the soleplate 202 measured just prior to undocking attime t0.

Once the steam iron 200 is re-docked, a measured temperature of T1 attime t1 would indicate 100% steam ironing, and from that a certainamount of water consumption during ironing can be determined (e.g. froma look-up table). A measured temperature of T3 at time t1 would indicate0% steam ironing (i.e. 100% dry ironing), which would imply no waterconsumption during ironing.

If the measured temperature is T2 at time t1, then it can be assumedthat the ironing performed by the user was a combination of dry ironingand steam ironing. The controller 253 can use the two reference curves 5a and 5 b to calculate the amount of water used to generate steam. Inparticular, as an example, the controller 253 can calculate two extremecases where the user could have gone to T2 by using least and mostamount of steaming (see curves 6 a and 6 b). These two numbers can beused by the controller 253 in order to decide how much water will be putin the water reservoir 201.

Preferably, the controller 253 is further adapted to determine, based onthe sensed soleplate temperature, a thermal energy amount to be storedin the soleplate 202 by the power supply unit 252, and to determine,based on the thermal energy amount, the amount of water to be suppliedto the water reservoir 201, such that the amount of water can be fullytransformed into steam by the thermal energy amount.

Preferably, the temperature sensor 203 is arranged in a location takenfrom the set of locations defined by the base unit 250 and the steamiron 200. The temperature sensor may correspond to a passive component(for example a so-called “NTC”). If the temperature sensor 203 isarranged in the steam iron, as illustrated in FIGS. 2a and 2b , thetemperature sensor 203 is electrically connected to the base unit 250when the steam iron in the first position P1. If the temperature sensor203 is arranged in the base unit 250, the steam iron must be adaptedsuch that the soleplate gets into contact with or proximate to thetemperature sensor 203 when the steam iron in the first position P1

Preferably, the controller 253 is arranged in a location taken from theset of locations defined by the base unit 250 and the steam iron 200. Ifthe controller 253 is arranged in the base unit 250, as illustrated inFIGS. 2a and 2b , the controller 253 is electrically connected to thebase unit 250.

Possibly, the controller 253 is arranged in the steam iron 200, and thecontroller 253 is electrically connected to a battery (not shown)arranged in the steam iron, which is for example charged when the steamiron is in the first position P1.

Preferably, the steam iron 200 comprises a heating element 204 forreceiving energy supplied by the power supply unit 252. The heatingelement 204 and the power supply unit 252 are adapted to be electricallyconnected when the steam iron 200 is in the first position P1.

Possibly, the base unit 250 comprises an induction system powered by thepower supply unit 252 for generating electromagnetic energy towards thesteam iron 200 when it is in the first position P1, which is convertedinto thermal energy in the steam iron 200 by metal or coil (not shown).

Preferably, the controller 253 is further adapted to generate a firstalert signal when the steam iron 200 is in the second position P2, ifthe time duration elapsed since the steam iron 200 was undocked from thefirst position P1 exceeds a given time duration threshold.

This signal is used to indicate the user to return the steam iron 200 tothe first position P1, for example after about 20 seconds when the steamiron is in the second position P2.

Preferably, the controller 253 is further adapted to generate a secondalert signal when the steam iron 200 is in the first position P1, afterthe sufficient thermal energy amount is stored in the soleplate 202 andthe matched amount of water supplied to the water reservoir 201.

For example, the first alert signal and the second alert signal maycorrespond to an alert via visual, audible, mechanical or other means.The alerts are generated to user via the user interfacing means 259 thatmay correspond to a display, a speaker, or a vibrating system.

The power supply 252 supplies power to the controller 253, the pump 251b, and the user interfacing means 259, as well as to other components ofthe base unit 250 controlled by the controller 253. Hence, the powersupply 252 powers various elements of the base unit 250. Also, asdiscussed below, when in the first position P1, the power supply 252supplies power to the heating element 204 and temperature sensor 203 inthe steam iron 200.

The operation of the ironing system 20 will be explained in more detailsin relation to FIG. 4.

At step S11 of FIG. 4, a user is performing cordless ironing using thesteam iron 200 in the second position P2. In this embodiment, no poweris provided to the heating element 204 when the in the second positionP2.

During cordless ironing, water from the water reservoir 201 is convertedto steam using heat from the soleplate 202. This depletes the amount ofwater in the water reservoir 201 and lowers the temperature of thesoleplate 202. In this embodiment, when the steam iron 200 is in thesecond position P2, water may be provided from the water reservoir 201to the soleplate 202 for steam ironing. Hence, steam may be generated bythe steam iron 200 in the second position P2. This can continue untilthe water reservoir 201 is emptied. In this example, ironing can be 100%steam ironing, dry ironing or a combination, though as discussed below,embodiments of the invention are not limited in this way.

In this embodiment, the steam iron 200 includes a mechanism (not shown)for ensuring that steam is generated only in the second position P2. Inthis embodiment, this mechanism (not shown) ensures that steam is notgenerated when the steam iron 200 is in the first position P1. It willbe appreciated that there are a variety of forms such a mechanism couldtake (e.g. a gravity controlled switch or mechanical valve), andembodiments of the invention are not limited in this way.

In this embodiment, the user may continue cordless ironing until anindication on the user interfacing means 259 informs the user to dockthe iron 200 on the base unit, otherwise directly dock the iron 200 onthe base unit before an indication on the user interfacing means 259 isgenerated.

At step S12, the user docks the steam iron 200 with the base unit 250.In other words, the user puts the steam iron 200 into the first positionP1. For example, the user may have ironed a portion of a garment and mayneed to rearrange the garment. At this point, the user may dock thesteam iron with the base unit.

Then at step S13, the controller 253 determines the temperaturevariation of the soleplate 202 by reading status of the temperaturesensor 203. In this embodiment, in the first position P1, the controller253 can get temperature reading from the temperature sensor 203 via theelectrical connection between the electrical interfaces 206 and 256 whenin the first position P1. In this embodiment, the temperature sensor 203comprises a thermistor in contact with the soleplate 202. However,embodiments of the invention can use other forms of temperature sensor.

In step S14, based on the sensed variation of temperature, thecontroller 253 calculates the amount of water consumed during ironingand how much water is left in the water reservoir 201.

Then, at step S15, the controller 253 controls the power supply 252 tosupply power to heat the soleplate 202 to a desired ironing temperature.In this embodiment, when in the first position P1, the power supply 252can supply electrical power to the heating element 204 via theelectrical connection between the electrical interfaces 206 and 256.

Thus, at step S15, the controller 253 controls the power supply 252 tosupply energy to heat the soleplate 202 to a desired temperature setpoint. The soleplate 202 is heated to a desired ironing temperature(e.g. 200° C.), based on information from the temperature sensor 203. Inthis embodiment, the temperature set point is a temperature (e.g. 200°C.) of the steam generator 202 b.

In this embodiment, the power of heating element 204 is fixed, and theON-OFF time of the heating element 204 is controlled by the controller253. In other words, the controller 253 varies the heating of theheating element 204 by controlling the supply of electrical power fromthe power supply 252. In other embodiments, the heating element 204 maybe controlled by the controller 253 to have varying heating power.

It can be assumed that whilst the steam iron 200 is in the secondposition P2, the main cause of temperature drop of the soleplate 202 isthe conversion of water to steam. As discussed, when in the secondposition P2, as an approximation, the drop in temperature of thesoleplate 202 can be related to the drop in water in the water reservoir201. As a result, the controller 253 can use the drop in temperature ofthe soleplate 202 to determine the amount of water left in the waterreservoir 201, without the need for a dedicated water sensor to detectthe level of water in the reservoir 201.

At step S16, the controller 253 calculates an amount of water to supplyto the water reservoir 201 via the connection between the waterinterfaces 205 and 255, as well as a flow rate of the pump 251 b basedon the calculated amount of water left in the water reservoir 201 fromstep S14.

The capacity of the water reservoir 201 is fixed (i.e. it is a designfeature) and the controller 253 may know that the water reservoir 201was filled the last time the steam iron 200 was docked to a certainlevel (e.g. full). Using this information, the controller 253 candetermine the amount of water left in the water reservoir 201 togetherwith the soleplate temperature information.

For example, by knowing the volume of water previously in the waterreservoir 201, the controller 253 can determine that a certain drop intemperature of the soleplate 202 equates to a temperature dropassociated with converting half the water in the water reservoir 201 tosteam, and thus the controller 253 can control the water reservoir 251to supply an amount of water equal to half the volume of the waterreservoir 201 to the water reservoir 201.

As a result, the amount of water supplied to the water reservoir 201 canbe supplied without needing a water sensor in the steam iron 200.

At step S17, the controller 253 controls the pump 251 b to supply waterto the water reservoir 201 via the connection between the waterinterfaces 205 and 225.

Preferably, steps S16 and S17 occur in parallel.

As a result, a suitable amount of water can supplied to the waterreservoir 201 by the pump 25 lb. This contrasts to using a conventionalsystem in which a pump in a dock is activated whenever the steam iron isdocked.

In a preferred embodiment, the pumping rate and time pattern of the pump251 b are variable. Using the above embodiment, achieving smooth andsoft charging patterns that minimize shocks and stress applied ontowater delivery system can be achieved.

The pumping rate transition may also be gradual. For example, by knowingthe amount of water needed to supply to the water reservoir 201, agradual pumping rate transition can be achieved, further minimisingstress on the system 20. For example, by gradual it is meant that theflow rate of water pumped to the water reservoir 201 in the steam irondecreases over time according to a given value known by the controller.

It may happen that a user only uses certain amount of the water in thewater reservoir 201. The controller 253 can determine that not all thewater is used, and rather than simply pumping the water to partiallyfull water reservoir 201 with high pumping rate and/or pressure withfull pumping time, the controller 253 can moderate pumping rate orshorten pumping time according to calculated water condition inreservoir. This minimize over pumping to reduce stress on the system 20.

It is preferred that heating of the heating element 204 and the supplyof the water to the water reservoir 201 are done simultaneously.Furthermore, the controller 253 can control the heating and waterpumping in a balanced way. Hence, the appropriate balance betweenthermal energy and water supply can be achieved. This balance can beobtained by not pumping more water to the water reservoir 201 thanthermal energy enough to convert the stored water in the water reservoir201 into steam. In other words, the amount of water and amount ofthermal energy can be matched.

The controller 253 can be arranged to control a water delivery rate ofthe pump 251 b so that a time taken to provide the required amount ofwater to the water reservoir 201 is the same as a time taken to supplythe required thermal energy amount to the soleplate 202.

At step S18, once the controller 253 has supplied sufficient water andpower to the steam iron 200 is in the first position P1, the steam iron200 is charged in water and thermal energy and is thus ready for moreironing. At this point, the readiness of the steam iron 200 isdisplayed, for example on the user interfacing means 259.

Hence, the user interfacing means 259 can alert the user when the steamiron 200 is ready for ironing. For example, the alert mechanism mayalert the user that the soleplate 202 is at the desired temperature andthat the water reservoir 201 is full. Hence, premature undocking may beavoided.

The user can then undock the steam iron 200 and can begin cordlessironing again (step S11), until the user interfacing means 259 indicatesthat is time to re-dock the steam iron 200, if the un-docking durationexceeds a given duration threshold. The user has the freedom to choosewhen to dock and undock, and that is not fixed by the appliance. Thesystem can record energy and water charged and lost condition by knowingcharged and used temperature as well as a time span to decide what to dofor next cycles.

In this embodiment, the water reservoir 201 has for example a volume of10 cm³. As an example, the steam iron 200 may generate a continuousamount of steam rate of 30 g/min in average for around 20 seconds whenin the second position P2 (for 100% steam ironing). It might typicallytake four minutes to iron one whole garment. With this volume for thewater reservoir, user should dock the steam iron 200 multiple times(e.g. around four to five times) to top up the water in the waterreservoir 201 and to re-heat the soleplate 202 during the ironingprocess. In this embodiment, in each cycle, water and energy are chargedin a balanced way, done by power and flow regulation.

According to the invention, a heating element 204 of 3200 Watts powermay be used, with a water reservoir 201 able to store 10 cm³ of waterafter previous charge-user cycle, with the soleplate 202 generatingsteam at an average 30 g/minute steam rate for 20 seconds, and a 500 gactive mass of the soleplate 202. The pump 251 b may be capable tosupply 120 g/minute, but it is preferably regulated to reduce pumpingrate to about 50 g/minute, to match with energy flow. As a result, itmight typically take about 11 seconds for the base unit 250 to provide abalanced amount of heat and water to the steam iron 200. If energy isfully consumed by last ironing cycles, known from temperature sensing,it may take around 15 seconds (i.e. of heating element 204 ON time) torecharge the energy (considering losses) of the soleplate 202. As aresult, the pumping rate of the pump 251 b may be adjusted to equivalent40 g/minute to make total energy balance. Whilst energy and water arebeing provided to the steam iron 20, the controller 253 performstemperature reading, energy balance calculations, heating element 204ON/OFF power control and pump 251 b ON/OFF rate control.

The ironing system may use a “safety factor” for the amount of waterdetermined by controller 253 and supplied to the water reservoir. Forexample the controller 253 may assume a certain error margin fordetermining the water amount (based on temperature and time, and in someembodiments usage patterns of the device) that has been consumed inironing. The controller may then control the supply of water to thesteam iron so that an amount of water is provided that is less than thecalculated water amount, while taking into account this error margin.

For an ironing session in which each ironing time after undocked isabout 30 second, the accuracy of such a system may be very high, as themajority of the energy is taken by steam generation. By readingtemperature change, as well as and time span preferably, the controller253 can correlation the energy loss to water consumption the amount ofwater used to generate steam, i.e. to cause temperature drop. In someembodiments, there is a water release path from the water reservoir 201,which allow excess water to pass in case there is over-charge of water.However, fully relying on such a water release path would increasestress in water delivery system during releasing. As a result, a systemwith only a water release path (and no fully accurate determination ofwater amount) would have increased stress compared to embodiments of theinvention.

In some embodiments, the controller 253 is further arranged to predictthe usage pattern of the steam iron 200 by using multiple temperaturechanges and time span information, for example, based on repeatedmeasurements, the controller 253 may estimate that the next movement ofthe user (e.g. with a certain mix of steam and dry ironing). Thecontroller 253 may store information on such a usage pattern and use itto estimate when call back is required.

As an example, if the controller 253 determines, based on repeatedmeasurements, that the user typically irons with 50% steam ironing and50% dry ironing, then the controller 253 can use stored data ontemperature/time to determine the time when the water reservoir 201 isgoing to be emptied and activate a call-back alert before then.

By activating a call back function, the user's ironing experience can beimproved. For example, the predetermined threshold can be set to be oneor two seconds before it is estimated by the controller 253 (e.g. basedon a starting water amount, e.g. 10 g for a full water reservoir 201)that the water reservoir 201 is going to be emptied. As a result, theuser can re-dock the steam iron 201 before steam producing performanceis reduced due to a lack of water and/or energy. This can help ensureoptimum ironing performance.

As shown in the flow chart of FIG. 5, the invention also relates to amethod of determining, in an ironing system 20 as described previouslyand comprising a steam iron 200 and a base unit 250, an amount of waterto be supplied from the base unit 250 to the steam iron 200, the baseunit 250 and the steam iron 200 being adapted to cooperate with eachother such that the steam iron 200 can take a first position P1 in whichthe steam iron 200 is docked on the base unit 250, and a second positionP2 in which the steam iron 200 is undocked from the base unit 250, thesteam iron 200 being cordlessly detached from the base unit 250 in thesecond position P2, the steam iron 200 comprising a water reservoir 201arranged to store water and a soleplate 202 for generating steam fromwater in the water reservoir 201 when the steam iron 200 is in thesecond position P2, the base unit 250 comprising water deliverymechanism 251 for supplying water to the water reservoir 201 when thesteam iron 200 is in the first position P1 and a power supply unit 252for supplying energy to the soleplate 202 when the steam iron 200 is inthe first position P1, for heating the soleplate 202.

The method comprises the steps of:

-   -   sensing SS1 the temperature of the soleplate 202,    -   determining SS2, based on a variation of temperature of the        soleplate, an amount of water to be supplied to the water        reservoir 201 by the water delivery mechanism 251.

Preferably, the step of determining SS2 comprises a step SS3 ofcalculating the variation of temperature between the temperature of thesoleplate 202 when the steam iron 200 is in a current first position P1,and the temperature of the soleplate 202 when the steam iron 200 was ina previous first position P1.

The above embodiments as described are only illustrative, and notintended to limit the technique approaches of the present invention.Although the present invention is described in details referring to thepreferable embodiments, those skilled in the art will understand thatthe technique approaches of the present invention can be modified orequally displaced without departing from the scope of the techniqueapproaches of the present invention, which will also fall into theprotective scope of the claims of the present invention. In the claims,the word “comprising” does not exclude other elements or steps, and theindefinite article “a” or “an” does not exclude a plurality. Anyreference signs in the claims should not be construed as limiting thescope.

1. An ironing system comprising a steam iron and a base unit adapted tocooperate with each other such that the steam iron can take a firstposition in which the steam iron is docked on the base unit, and asecond position in which the steam iron is undocked from the base unit,the steam iron being cordlessly detached from the base unit in thesecond position; wherein the steam iron comprises: a water reservoirarranged to store water, a soleplate for generating steam from water inthe water reservoir when the steam iron is in the second position,wherein the base unit comprises: a water delivery mechanism forsupplying water to the water reservoir when the steam iron is in thefirst position, a power supply unit for supplying energy to thesoleplate when the steam iron is in the first position, for heating thesoleplate, wherein the ironing system further comprises: a temperaturesensor for sensing temperature of the soleplate, wherein the ironingsystem also comprises: a controller for determining, based on avariation of temperature of the soleplate, an amount of water to besupplied to the water reservoir by the water delivery mechanism.
 2. Anironing system according to claim 1, wherein said variation oftemperature corresponds to the difference between the temperature of thesoleplate when the steam iron is in a current first position, and thetemperature of the soleplate when the steam iron was in a previous firstposition.
 3. An ironing system according to claim 2, wherein thecontroller is further adapted to determine said amount of water, basedon a time duration between two successive docking of the steam iron onthe base unit.
 4. An ironing system according to claim 1, wherein thecontroller is further adapted to determine, based on the sensedsoleplate temperature, a thermal energy amount to be stored in thesoleplate by the power supply unit, and to determine, based on saidthermal energy amount, said amount of water to be supplied to the waterreservoir, such that said amount of water can be fully transformed intosteam by said thermal energy amount.
 5. An ironing system according toclaim 1, wherein the temperature sensor is arranged in a location takenfrom the set of locations defined by the base unit and the steam iron.6. An ironing system according to claim 1, wherein the controller isarranged in a location taken from the set of locations defined by thebase unit and the steam iron.
 7. An ironing system according to claim 1,wherein the steam iron comprises a heating element for receiving energysupplied by the power supply unit.
 8. An ironing system according toclaim 7, wherein the heating element and the power supply unit areadapted to be electrically connected when the steam iron is in the firstposition.
 9. An ironing system according to claim 1, wherein the baseunit comprises an induction system powered by the power supply unit forgenerating electromagnetic energy towards the steam iron when the steamiron is in the first position.
 10. An ironing system according to claim1, wherein said controller is further adapted to generate a first alertsignal when the steam iron is in the second position, if the timeduration elapsed since the steam iron was unlocked from the firstposition exceeds a given time duration threshold.
 11. An ironing systemaccording to claim 4, wherein said controller is further adapted togenerate a second alert signal when the steam iron is in the firstposition, after the thermal energy amount is stored in the soleplate andthe amount of water supplied to the water reservoir.
 12. A method ofdetermining, in an ironing system comprising a steam iron and a baseunit, an amount of water to be supplied from the base unit to the steamiron, the base unit and the steam iron being adapted to cooperate witheach other such that the steam iron can take a first position in whichthe steam iron is docked on the base unit, and a second position inwhich the steam iron is undocked from the base unit, the steam ironbeing cordlessly detached from the base unit in the second position, thesteam iron comprising a water reservoir arranged to store water and asoleplate for generating steam from water in the water reservoir whenthe steam iron is in the second position, the base unit comprising waterdelivery mechanism for supplying water to the water reservoir when thesteam iron is in the first position and a power supply unit forsupplying energy to the soleplate a when the steam iron is in the firstposition, for heating the soleplate, the method being wherein itcomprises the steps of: sensing the temperature of the soleplate,determining, based on a variation of temperature of the soleplate, anamount of water to be supplied to the water reservoir by the waterdelivery mechanism.
 13. A method according to claim 12, wherein the stepof determining comprises a step of calculating the variation oftemperature between the temperature of the soleplate when the steam ironis in a current first position, and the temperature of the soleplatewhen the steam iron was in a previous first position.